Portal:Cetaceans
Cetaceans evolved from land mammals that adapted to marine life about 50 million years ago. Over a period of a few millions of years during the Eocene, the cetaceans returned to the sea. Their body is fusiform (spindle-shaped), the forelimbs are modified into flippers, the tiny hindlimbs are vestigial and the tail has horizontal flukes. Cetaceans are nearly hairless, and are insulated by a thick layer of blubber.
Cetaceans inhabit all of the world's oceans, as well as some rivers in South America and Asia. Some species can be found across the globe.
Cetology is the branch of marine science associated with the study of cetaceans.
The Sei Whale (Balaenoptera borealis) is a baleen whale, the third largest rorqual after the Blue Whale and the Fin Whale. It can be found worldwide in all oceans and adjoining seas, and prefers deep off-shore waters. It tends to avoid polar and tropical waters and semi-enclosed bodies of water. The Sei Whale migrates annually from cool and subpolar waters in summer to temperate and subtropical waters for winter, although in most areas the exact migration routes are not well known.
The whales reach lengths of up to 20 metres (66 ft) long and weigh up to 45 tonnes (50 tons). It consumes an average of 900 kilograms (2,000 lb) of food each day, primarily copepods and krill, and other zooplankton. It is among the fastest of all cetaceans, and can reach speeds of up to 50 kilometres per hour (31 mph) over short distances.
Following large-scale commercial hunting of the species between the late-nineteenth and late-twentieth centuries when over 238,000 individuals were taken, the Sei Whale is now an internationally protected species, although limited hunting still occurs under controversial research programmes conducted by Iceland and Japan. As of 2006, the worldwide population of the Sei Whale was about 54,000, about a fifth of its pre-whaling population.
More on the Sei Whale
2009 [edit]
February [edit]
- 10 February - Filipino fishermen have rescued around 200 melon-headed whales which were stranded in shallow waters off the coast of Bataan. Only three dolphins were reported to have died. more
January [edit]
- 24 January - The Cove, a feature-length film documenting the killing of dolphins in Taiji, Wakayama, wins the U.S. Audience Award at the 2009 Sundance Film Festival. more
- 22 January - A group of nearly 50 Sperm Whales beached on the northwest coast of the island of Tasmania in Australia. Only five were still alive by Friday afternoon. more
2008 [edit]
September [edit]
- 23 September - Speculation is raised over whether an object washed up near Wellington, New Zealand could be ambergris; City Council spokesman Richard MacLean says this is unlikely. Read more...
- 17 September - A man in Trefriw, Wales pleads guilty to the uncertified selling of a Harbour Porpoise skull on eBay. Read more...
- 10 September - Australia and New Zealand announce a non-lethal whale research program to challenge Japan's whaling. Read more...
August [edit]
- 26 August - Findings from the controversial Japanese whaling research program suggest that a loss of Antarctic sea ice due to increased temperatures has lowered whales' food supply, causing an overall decline in blubber. Read more...
- 12 August - IUCN changes the conservation status of the Humpback Whale and Southern Right Whale to "least concern" due to the species' recovery. Read more...
- 1 August - Snubfin Dolphins are recorded on camera for the first time along the Australian coastline. Read more...
- ...dolphins often leap clear of the water when travelling at speed. This is because the density of water is much greater than that of air and they are able to travel faster by leaping out of the water.
- ...both whales and dolphins carry ‘whale lice’ — small crustaceans that inhabit folds in the skin of whales and dolphins, feeding off the loose skin.
- ...whale and dolphin mothers ‘suckle’ their young underwater! Mothers have muscular mammary glands and ‘squirt’ their milk into the calf’s mouth, to ensure that the calf takes in as much of the energy rich milk as possible.
- ...on average, a whale or dolphin will eat four to five percent of its body weight in food per day. That means that a 100 ton blue whale will eat almost five tons of krill per day, or that a 200kg bottlenose dolphin will eat 10kg of fish per day!
- ...newborn cetacean calves ‘suckle’ three to four times each hour and will suckle from their mothers for six months or more.
Subcategories of Cetaceans:
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Humpback Whales blow a curtain of bubbles around their prey and then lunge through them with their mouths open. The Humpbacks strain the tiny creatures, called krill, through the baleen in their mouths.
More on lunge-feeding
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Recorded by the National Park Service, using a hydrophone that is anchored near the mouth of Glacier Bay, Alaska for the purpose of monitoring ambient noise.
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